Method For Preparing Spherical Or Angular Powder Filler, Spherical Or Angular Powder Filler Obtained Therefrom, And Use Thereof

ABSTRACT

The present invention relates to a method for preparing a spherical or angular powder filler, comprising providing a spherical or angular siloxane comprising T units; performing a heat treatment on the spherical or angular siloxane, the heat treatment temperature between 250° C. and the temperature of oxidative decomposition of organic groups, so that silicon hydroxyl groups in the spherical or angular siloxane are condensed to obtain a condensed siloxane; and adding a treatment agent to treat the condensed siloxane to promote the condensation of silicon hydroxyl groups in the condensed siloxane to give a spherical or angular powder filler, the treatment agent comprising a silane coupling agent and/or disilazane, and the quotient of the molecular weight of at least a portion of the silane coupling agent and/or the disilazane divided by its specific gravity at 25° C. being less than or equal to 210. The present invention also provides a spherical or angular powder filler obtained therefrom. The present invention further provides use of above spherical or angular powder filler. The filler provided by the present invention has low permittivity, low permittivity loss, without conductive impurities, without coarse oversize particles, and low radioactivity.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates generally to semiconductor packages, andmore particularly to a method for preparing a spherical or angularpowder filler, spherical or angular powder filler obtained therefrom,and use thereof.

2. Related Art

In the packaging step of the semiconductor back-end process, packagingmaterials are required, such as molding compound, patch glue, underfillmaterial or chip carrier. In addition, circuit boards, such as highdensity interconnects (HDI), high-frequency high-speed boards ormotherboards, are required when assembling an equipment from devices,such as passive elements, semiconductor elements, electro-acousticcomponents, display components, optical components or radio frequencycomponents. These packaging materials and circuit boards are mainlycomposed of organic polymers, such as epoxy resin, aromatic polyether orfluororesin, and fillers. The filler is generally spherical or angularsilicon dioxide, and its main function is to reduce the thermalexpansion coefficient of the organic polymer. The existing filler istightly packed from spherical or angular silicon dioxide, wherein thechemical structure of the silicon dioxide is Q unit of Si, i.e., SiO₄—.

On the one hand, along with the technology progress, the signalfrequency used by semiconductors is getting higher and higher, and thehigh-speed and low-loss signal transmission requires fillers with lowpermittivity and low permittivity loss. On the other hand, thepermittivity (also known as dielectric constant) and permittivity loss(also known as dielectric loss) of the material basically depend on thechemical composition and structure of the material. Silicon dioxide hasits inherent permittivity and permittivity loss. Therefore, the existingfiller cannot meet the requirement of lower permittivity and lowerpermittivity loss.

Similarly, along with the technology progress, the integration ofsemiconductors is getting higher and higher, and the smaller and smallersize requires fillers with high purity, without conductive impuritiesand without coarse oversize particles. However, it is difficult to avoidthe coarse oversize particles and conductive impurities in the existingspherical or angular silicon dioxide. Moreover, once coarse oversizeparticles and conductive impurities have been mixed, they cannot beremoved by dry methods. Therefore, the existing filler cannot meet therequirement without conductive impurities and without coarse oversizeparticles.

For semiconductor memories, the filler is required to have lowradioactivity. However, the existing spherical or angular silicondioxide has a purity largely depending on the purity of naturalminerals. Therefore, the existing filler cannot meet the requirement oflow radioactivity.

SUMMARY OF THE INVENTION

The present invention provides a method for preparing a spherical orangular powder filler, a spherical or angular powder filler obtainedtherefrom, and use thereof. The provided filler has low permittivity,low permittivity loss, without conductive impurities, without coarseoversize particles and with low radioactivity.

The present invention provides a method for preparing a spherical orangular powder filler, comprises: S1, providing a spherical or angularsiloxane comprising T units, wherein the T unit=RiSiO₃—, and R₁ is ahydrogen atom or an organic group independently selected from C₁-C₁₈;S2, performing a heat treatment on the spherical or angular siloxane,the heat treatment temperature between 250° C. and the temperature ofoxidative decomposition of the organic group, so that silicon hydroxylgroups in the spherical or angular siloxane are condensed to obtain acondensed siloxane; and S3, adding a treatment agent to treat thecondensed siloxane to promote the condensation of silicon hydroxylgroups in the condensed siloxane to give a spherical or angular powderfiller, the treatment agent comprising a silane coupling agent and/ordisilazane, the weight percentage of the treatment agent being 0.5-50 wt%, and the quotient of the molecular weight of at least a portion of thesilane coupling agent and/or the disilazane divided by its specificgravity at 25° C. being less than or equal to 210.

Different from the existing silicon dioxide filler only containing Qunits, the silicon dioxide of the spherical or angular powder filler ofthe present invention comprises T units, wherein the introduction oforganic group R greatly reduces the permittivity and the permittivityloss. In addition, since the T unit has only three SiOSi bridgingpoints, its thermal expansion coefficient is higher than that of the Qunit of silicon dioxide. Therefore, an appropriate amount of Q units canbe introduced as needed to adjust the balance of the permittivity, thepermittivity loss and the thermal expansion coefficient. Although thecondensed siloxane obtained by the heat treatment has a high degree ofcondensation by heating, new isolated outer surface Si—OHs and internalcracked surface Si—OHs (also collectively referred to as surface Si—OHs)are produced due to the spatial geometric limitation, therefore, thetreatment agent is subsequently added to promote the condensation ofsurface Si—OHs of the siloxane, thereby further reducing thepermittivity and the permittivity loss. Specifically, the silanecoupling agent or disilazane, the quotient of whose molecular weightdivided by its specific gravity at 25° C. is less than or equal to 210,can enter the internal cracks of the powder due to its small molecule,and thus can promote the condensation of the internal cracked surfaceSi—OHs.

Preferably, the spherical or angular siloxane of S1 further comprises Qunits, D units, and/or M units, wherein the Q unit=SiO₄—, Dunit=R₂R₃SiO₂—, M unit=R₄R₅R₆SiO₂—, and R₂, R₃, R₄, R₅, R₆ each is ahydrogen atom or a hydrocarbyl independently selected from C₁-C₁₈. Itshould be understood that the introduction of Q units can reduce thethermal expansion coefficient, but will increase the permittivity andthe permittivity loss, so the introduction amount should be adjusted asneeded. In addition, the introduction of D or M units can reduce thepermittivity and the permittivity loss, but will increase the thermalexpansion coefficient, so the introduction amount should be adjusted asneeded. Preferably, the total content of Q units, D units, and/or Munits in the spherical or angular siloxane is ≤20 wt %.

Preferably, the spherical or angular siloxane of S1 further comprisessilicon dioxide particles. It should be understood that the introductionof silicon dioxide particles (also known as silicon dioxide fine powder)can reduce the thermal expansion coefficient, but will increase thepermittivity and the permittivity loss, so the introduction amountshould be adjusted as needed. Preferably, the total content of silicondioxide particles in the spherical or angular siloxane is ≤70 wt %.

In preferred embodiments, the average particle size of the spherical orangular siloxane of S1 is 0.5-50 μm. In a preferred embodiment, theaverage particle size of the spherical or angular siloxane is 2 μm.

In preferred embodiments, the spherical or angular siloxane comprises97% of spherical siloxane of T units and 3% of spherical siloxane of Qunits or D units. In a preferred embodiment, the spherical or angularsiloxane comprises 100% of spherical siloxane of T units. In a preferredembodiment, the spherical or angular siloxane comprises 100% of angularsiloxane of T units. In a preferred embodiment, the spherical or angularsiloxane comprises 70% of angular siloxane of T units and 30% of silicondioxide particles.

In a preferred embodiment, R₁ of the T unit is methyl or vinyl.

Preferably, in S2, the heat treatment is realized by electric heating ormicrowave heating, wherein the Si—OHs of the spherical or angularsiloxane are condensed to produce the SiOSi structure. The equation ofthe condensation reaction is as follows:

Wherein R′, R″, R′″ each is a hydrogen atom or an organic group R₁ (alsoknown as hydrocarbyl) independently selected from C₁-C₁₈.

Preferably, the heat treatment temperature of S2 is 250-400° C. Mostpreferably, the temperature is 250-320° C. It should be understood thattoo low temperature will result in incomplete Si—OHs condensationreaction, while too high temperature will result in decomposition oforganic groups. For example, because the decomposition temperature ofthe phenyl group is relatively high, when the organic group is thephenyl group, the corresponding heat treatment temperature is higherthan when the organic group is the alkyl. In preferred embodiments, theheat treatment time is 30 min-24 h. It should be understood that whenthe temperature is higher, the required time is shorter, vice versa. Inpreferred embodiments, the heat treatment time is between 1-20 h.

Preferably, the silane coupling agent of S3 is at least one agentselected from silane coupling agent (R₇)_(a)(R₈)_(b)Si(M)_(4-a-b)wherein R₇, R₈ each is a hydrogen atom, a hydrocarbyl independentlyselected from C₁-C₁₈, or a hydrocarbyl independently selected fromC₁-C₁₈ replaced by functional groups, and the functional group is atleast one group selected from the group consisting of following organicfunctional groups: vinyl, allyl, styryl, epoxy group, aliphatic amino,aromatic amino, methacryloxypropyl, acryloxypropyl, ureidopropyl,chloropropyl, mercapto propyl, polysulfide, isocyanate propyl; M is analkoxy group of C₁-C₁₈ or a halogen atom, a=0, 1, 2 or 3, b=0, 1, 2 or3, and a+b=1, 2 or 3.

Preferably, the silane coupling agent is a silane coupling agent withfree radical polymerization reaction, such as vinyl silane couplingagent; a silane coupling agent reacting with epoxy resin, such as epoxysilane coupling agent, or amino silane coupling agent; a hydrocarbylsilane coupling agent with high affinity to hydrophobic resins, such asdimethyldimethoxysilane, diphenyldimethoxysilane, phenyl silane couplingagent, or long-chain alkyl silane coupling agent. More preferably, thesilane coupling agent is at least one coupling agent selected from thegroup consisting of: dimethyldimethoxysilane, methyltrimethoxysilane,phenyltrimethoxysilane, and vinyltrimethoxysilane. In particular, thesilane coupling agent cannot be 100% of3-methacryloxypropyltrimethoxysilane, nor 100% of hexyltrimethoxysilane(the molecular weight of the silane coupling agent is 206.35, itsspecific gravity at 25° C. is 0.92, and the quotient of the molecularweight divided by its specific gravity at 25° C. is 224.3, above 210).

Preferably, the disilazane of S3 is at least one agent selected fromdisilazane (R₉R₁₀R₁₁)SiNHSi(R₁₂R₁₃R₁₄), wherein R₉, R₁₀, R₁₁, R₁₂, R₁₃,R₁₄ each is a hydrogen atom or a hydrocarbyl independently selected fromC₁-C₁₈. More preferably, the disilazane is hexamethyldisilazane.

In preferred embodiments, the addition amount of the treatment agent instep S3 is 8-12 wt %. In a preferred embodiment, the addition amount ofthe treatment agent in step S3 is 10 wt %. In a preferred embodiment,the silicon hydroxyl groups in the condensed siloxane are condensed at180° C. for 6 h.

Preferably, the method comprises removing coarse oversize particlesabove 75 μm in the spherical or angular powder filler by dry or wetsieving or inertial classification. Preferably, coarse oversizeparticles above 55 μm in the spherical or angular powder filler areremoved by dry or wet sieving or inertial classification. Preferably,coarse oversize particles above 45 μm in the spherical or angular powderfiller are removed by dry or wet sieving or inertial classification.Preferably, coarse oversize particles above 20 μm in the spherical orangular powder filler are removed by dry or wet sieving or inertialclassification. Preferably, coarse oversize particles above 10 μm in thespherical or angular powder filler are removed by dry or wet sieving orinertial classification. Preferably, coarse oversize particles above 5μm in the spherical or angular powder filler are removed by dry or wetsieving or inertial classification. Preferably, coarse oversizeparticles above 3 μm in the spherical or angular powder filler areremoved by dry or wet sieving or inertial classification. Preferably,coarse oversize particles above 1 μm in the spherical or angular powderfiller are removed by dry or wet sieving or inertial classification.

The present invention also provides a spherical or angular powder fillerobtained by above method, wherein the spherical or angular powder fillerhas a particle size of 0.1-50 μm, the volatile moisture content of thespherical or angular powder filler at 200° C. is less than or equal to3000 ppm. Preferably, the particle size is 0.5-30 μm. The presentinvention provides silane coupling agent or disilazane with smallermolecular to block internal cracks, in order to reduce the moisturecontent of the powder, thereby avoiding the increase of the permittivityand the permittivity loss. In particular, the moisture content of thepowder of the present invention can be calculated by Karl Fischermoisture at 200° C.

The measurement results show that the permittivity of the spherical orangular powder filler of the present invention at 500 MHz is only2.5-2.8, which is less than 3, while the permittivity of the existingsilicon dioxide filler of Q units is about 3.8-4.5. Therefore, thespherical or angular powder filler of the present invention has agreatly reduced permittivity, and can meet the material requirement ofhigh-frequency signal in the 5G era.

The measurement results show that the permittivity loss of the sphericalor angular powder filler of the present invention at 500 MHz is only0.0005 to 0.002, which is less than 0.005, while the permittivity lossof the existing silicon dioxide filler of Q units is about 0.003-0.01.Therefore, the spherical or angular powder filler of the presentinvention has a greatly reduced permittivity loss, and can meet thematerial requirement of high-frequency signal in the 5G era.

The measurement results show that the thermal expansion coefficient ofthe spherical or angular powder filler of the present invention is 5-15ppm, while the thermal expansion coefficient of the existing fusedsilicon dioxide is about 0.5 ppm, and the thermal expansion coefficientof the existing crystalline silicon dioxide (quartz) is 8-13 ppm.Therefore, the spherical or angular powder filler of the presentinvention has an equivalent thermal expansion coefficient to generalinorganic filler, and can meet the material requirement ofhigh-frequency signal in the 5G era.

The present invention further provides use of above spherical or angularpowder filler, wherein the spherical or angular powder filler ofdifferent particle sizes is tightly packed in the resin to form acomposite material. Preferably, the composite material is suitable forsemiconductor packaging materials, circuit boards and intermediatesemi-finished products. Preferably, the packaging material is moldingcompound, patch glue, underfill material or chip carrier. The moldingcompound is DIP package molding compound, SMT package molding compound,MUF, FO-WLP, or FCBGA molding compound. Preferably, the circuit board isHDI, high-frequency high-speed board, or motherboard.

It is known that the thermal expansion coefficient of the compositematerial can be approximately calculated by the following formula 1:

α=V ₁×α₁ +V ₂×α₂  Formula 1

α: the thermal expansion coefficient of the composite material; V₁: thevolume fraction of the resin; α₁: the thermal expansion coefficient ofthe resin; V₂: the volume fraction of the filler; and α₂: the thermalexpansion coefficient of the filler.

The thermal expansion coefficient α₁ of the resin is 60-120 ppm. Thethermal expansion coefficient α₂ of the spherical or angular powderfiller of the present invention is 5-15 ppm, much lower than the thermalexpansion coefficient of the resin, which can reduce the thermalexpansion coefficient of the cured resin composition like the existinginorganic filler, in order to match the thermal expansion of the wiremetal or wafer. Therefore, by adjusting the volume fraction of the resinand the spherical or angular powder filler, the thermal expansioncoefficient of the composite material can be designed to form thepackaging material, circuit board and intermediate semi-finishedproduct.

It is known that the permittivity of the composite material can beapproximately calculated by the following formula 2:

logε=V ₁×logε₁ +V ₂×logε₂  Formula 2

ε: the permittivity of the composite material; V₁: the volume fractionof the resin; ε₁: the permittivity of the resin; V₂: the volume fractionof the filler; and ε₂: the permittivity of the filler.

Therefore, by adjusting the volume fraction of the resin and thespherical or angular powder filler, the permittivity of the compositematerial can be designed to form the packaging material, circuit boardand intermediate semi-finished product.

In addition, the permittivity loss of the composite material isdetermined by the permittivity loss of the resin and the filler, and thenumber of polar groups on the surfaces of the filler. The spherical orangular powder filler according to the present invention has lowpermittivity and less polar groups on the surfaces of the filler,therefore, the composite material has low permittivity loss.

In a word, the spherical or angular powder filler obtained according toabove method of the present invention has low permittivity and lowpermittivity loss. Moreover, since the raw materials of the method areall organic materials without involving the conventionally used angularcrushed quartz, etc., and the product can be refined by industrialmethods such as distillation, the obtained spherical or angular powderfiller does not contain radioactive elements such as uranium or thorium,meeting the requirement without conductive impurities, without coarseoversize particles, and of low radioactivity. Further, the synthesisparameters of method of the present invention can be appropriatelyadjusted to produce the spherical or angular powder filler with aparticle size of 0.1-50 μm.

DESCRIPTION OF THE ENABLING EMBODIMENT

The preferred embodiments of the present invention are given below anddescribed in detail.

The detection methods involved in the following embodiments include:

The average particle size is measured by a laser particle sizedistribution instrument HORIBA LA-700, and the solvent is isopropanol;

The specific surface area is measured by SHIMADZU FlowSorbIII2305;

The true specific gravity is measured by MicrotracBEL BELPycno;

The thermal expansion coefficient of the filler is calculated from theknown thermal expansion coefficient and true specific gravity of epoxyresin, the true specific gravity of the filler, and the measured thermalexpansion coefficient of a resin sample containing a certain amount offiller.

Uranium or thorium content is measured by Agilent 7700X ICP-MS. Thesample is prepared by total dissolution in hydrofluoric acid afterburning at 800° C.;

The volatile moisture content at 200° C. is measured by MitsubishiChemical CA-310 Karl Fischer automatic analyzer with heated vaporizer.

The content of Q, T, D, or M units is measured by solid ²⁸Si-NMR nuclearmagnetic resonance spectrum of JEOL ECS-400 Nuclear magnetic resonanceinstrument, wherein the Q unit content is calculated from the peakintegrated area between −80 ppm and −120 ppm; the T unit content iscalculated from the peak integrated area between −30 ppm and −80 ppm;the D unit content is calculated from the peak integrated area between−10 ppm and −30 ppm; and the M unit content is calculated from the peakintegrated area between +20 ppm and −10 ppm; referring to Separation andPurification Technology Volume 25, Issues 1-3, Oct. 1, 2001, Pages391-397, ²⁹ Si NMR and Si2p XPS correlation in polysiloxane membranesprepared by plasma enhanced chemical vapor deposition.

The permittivity or the permittivity loss is measured by KEYCOMpermittivity and permittivity loss measuring device Model No. DPS18 inperturbation method and sample hole block-shaped cavity resonancemethod.

In this text, temperature degree refers to “degrees Celsius”, that is, °C.

Referring to “Spherical Silicone Resin Micropowder”, Huang Wenrun,Organic Silicone Materials, 2007, 21 (5) 294-299, the spherical siloxaneof different compositions in Examples and Comparative Examples isprepared for subsequent heat treatment.

Methyltrichlorosilane or methyltrimethoxysilane was added into water toprovide a white precipitate. After being washed with deionized water,the precipitate was ground by a sand mill to a fine powder of 2 μm inExamples and Comparative Examples for subsequent heat treatment.

In addition, methyltrichlorosilane or methyltrimethoxysilane was mixedwith silicon dioxide, and the mixture was added into water to provide awhite precipitate. After being washed with deionized water, theprecipitate was ground by a sand mill to a fine powder of 2 μm inExamples and Comparative Examples for subsequent heat treatment.

Example 1

The spherical siloxane of 100% T units (R₁ is methyl) with a particlesize of 2 μm was heat treated in an air atmosphere at differenttemperatures. The treated powder was mixed with 10%methyltrimethoxysilane (the molecular weight of the silane couplingagent is 136.22, its specific gravity at 25° C. is 0.955, and thequotient of the molecular weight divided by its specific gravity at 25°C. is 142.6, which is less than 210), the mixture was heated at 180° C.for 6 h, and the powder was separated by cyclone to remove coarseoversize particles above 10 μm to obtain samples of Examples andComparative Examples. The analysis results of the samples are listed inTable 1.

TABLE 1 Composition of Spherical Evaporated Thermal Siloxane AverageHeat Water Permittivity Expansion T unit Q unit Particle Heat TreatmentTreatment Volume at Permittivity Loss Coefficient wt % wt % Size μmTemperature ° C. Time h 200° C. ppm 500 MHz 500 MHz ppm Example 1 100 02.0 250 20 2900 2.9 0.002 12 Example 2 100 0 2.0 280 20 2000 2.7 0.00110 Example 3 100 0 2.0 320 20 900 2.6 <0.001 8 Comparative 100 0 2.0 20020 15000 3.9 0.01 17 Example 1 Comparative 100 0 2.0 450 20 2500 4.90.01 6 Example 2 Comparative 100 0 2.0 650 20 1000 5.1 0.01 6 Example 3

Obviously, the permittivity of each of the samples obtained according toExample 1-Example 3 is less than 3, and the permittivity loss each isless than 0.005, meeting the requirement of low permittivity (lesssignal delay) and low permittivity loss (less signal loss) of the fillerin the 5G era. The heat treatment temperature of Comparative Example 1is too low and the heat treatment temperature of Comparative Examples2-3 is too high, wherein the permittivity each is above 3, and thepermittivity loss each is above 0.005, failing to meet the requirementof low permittivity (less signal delay) and low permittivity loss (lesssignal loss) of the filler in the 5G era.

Example 2

The spherical siloxane of 97% T units (R₁ is methyl) and 3% Q units witha particle size of 2 μm was heat treated in an air atmosphere. Thetreated powder was mixed with 8% methyltrimethoxysilane and then mixedwith 2% 3-methacryloxypropyltrimethoxysilane, the mixture was heated at180° C. for 6 h, and the powder was separated by cyclone to removecoarse oversize particles above 10 μm to obtain samples of Examples andComparative Examples. The analysis results of the samples are listed inTable 2. The Comparative Example 4 differs from Example 4 withoutmethyltrimethoxysilane, and the Comparative Example 5 differs fromExample 4 only with 3-methacryloxypropyltrimethoxysilane (the molecularweight of the silane coupling agent is 248.35, its specific gravity at25° C. is 1.045, and the quotient of the molecular weight divided by itsspecific gravity at 25° C. is 237.7, which is above 210).

TABLE 2 Composition of Spherical Evaporated Thermal Siloxane AverageHeat Water Permittivity Expansion T unit Q unit Particle Heat TreatmentTreatment Volume at Permittivity Loss Coefficient wt % wt % Size μmTemperature ° C. Time h 200° C. ppm 500 MHz 500 MHz ppm Example 4 97 32.0 280 20 1200 2.7 <0.001 9 Comparative 97 3 2.0 280 20 3500 3.3 0.0099 Example 4 Comparative 97 3 2.0 280 20 3600 3.4 0.009 9 Example 5

Obviously, the permittivity of the sample obtained according to Example4 is less than 3, and the permittivity loss is less than 0.005, meetingthe requirement of low permittivity (less signal delay) and lowpermittivity loss (less signal loss) of the filler in the 5G era. TheComparative Example 4 without silane coupling agent for condensingsilicon hydroxyl groups and the Comparative Example 5 with silanecoupling agent, the quotient of whose molecular weight divided by itsspecific gravity at 25° C. is above 210, for condensing silicon hydroxylgroups provide the samples with permittivity above 3 and permittivityloss above 0.005, failing to meet the requirement of low permittivity(less signal delay) and low permittivity loss (less signal loss) of thefiller in the 5G era.

Example 3

The spherical siloxane of 97% T units (R₁ is methyl) and 3% D units (R₂,R₃ each is methyl) with a particle size of 2 μm was heat treated in anair atmosphere. The treated powder was mixed with 10%hexamethyldisilazane (the molecular weight of the disilazane is 161.39,its specific gravity at 25° C. is 0.774, and the quotient of themolecular weight divided by its specific gravity at 25° C. is 208.5,which is less than 210), the mixture was heated at 180° C. for 6 h, andthe powder was separated by cyclone to remove coarse oversize particlesabove 10 μm to obtain the sample of Example. The analysis results of thesample are listed in Table 3.

TABLE 3 Composition of Spherical Evaporated Thermal Siloxane AverageHeat Water Permittivity Expansion T unit D unit Particle Heat TreatmentTreatment Volume at Permittivity Loss Coefficient wt % wt % Size μmTemperature ° C. Time h 200° C. ppm 500 MHz 500 MHz ppm Example 5 97 32.0 280 20 800 2.7 <0.001 10

Obviously, the permittivity of the sample obtained according to Example5 is less than 3, and the permittivity loss is less than 0.005, meetingthe requirement of low permittivity (less signal delay) and lowpermittivity loss (less signal loss) of the filler in the 5G era.

Example 4

Methyltrimethoxysilane and silicon dioxide were mixed and then addedinto water to provide a white precipitate. After being washed withdeionized water, the precipitate was ground by a sand mill to a finepowder of 2 μm.

The angular siloxane of 70% T units (R₁ is methyl) and 30% silicondioxide fine powder (gas phase white carbon black) with a particle sizeof 2 μm was heat treated in an air atmosphere. The treated powder wasmixed with 10% dimethyldimethoxysilane (the molecular weight of thedisilazane is 120.22, its specific gravity at 25° C. is 0.88, and thequotient of the molecular weight divided by its specific gravity at 25°C. is 136.6, which is less than 210), the mixture was heated at 180° C.for 6 h, and the powder was separated by cyclone to remove coarseoversize particles above 10 μm to obtain the sample of Example. Theanalysis results of the sample are listed in Table 4.

TABLE 4 Composition of Angular Siloxane Evaporated Thermal siliconAverage Heat Water Permittivity Expansion T unit dioxide Particle HeatTreatment Treatment Volume at Permittivity Loss Coefficient wt % wt %Size μm Temperature ° C. Time h 200° C. ppm 500 MHz 500 MHz ppm Example6 70 30 2.0 280 20 900 2.9 <0.001 3

Obviously, the permittivity of the sample obtained according to Example6 is less than 3, and the permittivity loss is less than 0.005, meetingthe requirement of low permittivity (less signal delay) and lowpermittivity loss (less signal loss) of the filler in the 5G era.

Example 5

The spherical siloxane of 100% T units (R₁ is methyl) with a particlesize of 2 μm was heat treated in an air atmosphere. The treated powderwas mixed with 8% vinyltrimethoxysilane (the molecular weight of thedisilazane is 148.23, its specific gravity at 25° C. is 0.971, and thequotient of the molecular weight divided by its specific gravity at 25°C. is 152.7, which is less than 210) and then mixed with 4%hexamethyldisilazane, the mixture was heated at 180° C. for 6 h, and thepowder was separated by cyclone to remove coarse oversize particlesabove 10 μm to obtain the sample of Example 7. The analysis results ofthe sample are listed in Table 5.

The spherical siloxane of 100% T units (R₁ is methyl) with a particlesize of 2 μm was heat treated in an air atmosphere. The treated powderwas mixed with the mixture of 8% phenyltrimethoxysilane (the molecularweight of the disilazane is 198.29, its specific gravity at 25° C. is1.062, and the quotient of the molecular weight divided by its specificgravity at 25° C. is 186.7, which is less than 210) and 4%hexamethyldisilazane, the mixture was heated at 180° C. for 6 h, and thepowder was separated by cyclone to remove coarse oversize particlesabove 10 μm to obtain the sample of Example 8. The analysis results ofthe sample are listed in Table 5.

TABLE 5 Composition of Spherical Evaporated Thermal Siloxane AverageHeat Water Permittivity Expansion T unit Q unit Particle Heat TreatmentTreatment Volume at Permittivity Loss Coefficient wt % wt % Size μmTemperature ° C. Time h 200° C. ppm 500 MHz 500 MHz ppm Example 7 100 02.0 280 20 1900 2.6 <0.001 9 Example 8 100 0 2.0 280 20 1800 2.8 <0.0019

Obviously, the permittivity of each of samples obtained according toExample 7-Example 8 is less than 3, and the permittivity loss is lessthan 0.005, meeting the requirement of low permittivity (less signaldelay) and low permittivity loss (less signal loss) of the filler in the5G era.

Example 6

The spherical siloxane of 100% T units (R₁ is vinyl) with a particlesize of 2 μm was heat treated in an air atmosphere. The treated powderwas mixed with 8% hexamethyldisilazane, the mixture was heated at 180°C. for 6 h, and the powder was separated by cyclone to remove coarseoversize particles above 10 μm to obtain the sample of Example 9. Theanalysis results of the sample are listed in Table 6.

The spherical siloxane of 100% T units (R₁ is methyl) with a particlesize of 2 μm was heat treated in an air atmosphere. The treated powderwas mixed with 4% phenyltrimethoxysilane, the mixture was heated at 180°C. for 6 h, and the powder was separated by cyclone to remove coarseoversize particles above 10 μm to obtain the sample of Example 10. Theanalysis results of the sample are listed in Table 6.

TABLE 6 Composition of Spherical Evaporated Thermal Siloxane AverageHeat Water Permittivity Expansion T unit Q unit Particle Heat TreatmentTreatment Volume at Permittivity Loss Coefficient wt % wt % Size μmTemperature ° C. Time h 200° C. ppm 500 MHz 500 MHz ppm Example 9 100 02.0 250 20 2500 2.6 <0.001 9 Example 10 100 0 2.0 300 20 1000 2.9 <0.0019

Obviously, the permittivity of each of samples obtained according toExample 9-Example 10 is less than 3, and the permittivity loss is lessthan 0.005, meeting the requirement of low permittivity (less signaldelay) and low permittivity loss (less signal loss) of the filler in the5G era.

Example 7

The spherical siloxane of 100% T units (R₁ is methyl) with differentparticle sizes was heat treated in an air atmosphere in different time.The treated powder was mixed with 8% methyltrimethoxysilane, the mixturewas heated at 180° C. for 6 h to obtain samples of Examples. Theanalysis results of the sample are listed in Table 7.

TABLE 7 Composition of Spherical Evaporated Thermal Siloxane AverageHeat Water Permittivity Expansion T unit Q unit Particle Heat TreatmentTreatment Volume at Permittivity Loss Coefficient wt % wt % Size μmTemperature ° C. Time h 200° C. ppm 500 MHz 500 MHz ppm Example 11 100 00.5 290 1 800 2.60 <0.001 10 Example 12 100 0 2.0 290 3 800 2.61 <0.00110 Example 13 100 0 10 290 7 800 2.60 <0.001 9 Example 14 100 0 30 29015 800 2.60 <0.001 9 Example 15 100 0 50 290 20 800 2.59 <0.001 8

Obviously, the permittivity of each of samples obtained according toExample 11-Example 15 is less than 3, and the permittivity loss is lessthan 0.005, meeting the requirement of low permittivity (less signaldelay) and low permittivity loss (less signal loss) of the filler in the5G era.

Example 8

Methyltrichlorosilane was added into water to provide a whiteprecipitate. After being washed with deionized water, the precipitatewas ground by a sand mill to a fine powder of 2 μm, filtrated, dried andheat treated in a nitrogen atmosphere. The treated powder was mixed with15% methyltrimethoxysilane, the mixture was heated at 180° C. for 6 h,and the powder was separated by cyclone to remove coarse oversizeparticles above 10 μm to obtain the sample of Example. The analysisresults of the sample are listed in Table 8.

TABLE 8 Composition of Spherical Evaporated Thermal Siloxane AverageHeat Water Permittivity Expansion T unit Q unit Particle Heat TreatmentTreatment Volume at Permittivity Loss Coefficient wt % wt % Size μmTemperature ° C. Time h 200° C. ppm 500 MHz 500 MHz ppm Example 16 100 02.0 280 20 900 2.9 0.005 11

Obviously, the permittivity of the sample obtained according to Example16 is less than 3, and the permittivity loss is less than 0.005, meetingthe requirement of low permittivity (less signal delay) and lowpermittivity loss (less signal loss) of the filler in the 5G era.

It should be understood that samples of above Example 1-Example 16 canbe vertex cut to remove coarse oversize particles. Specifically, coarseoversize particles above 1, 3, 5, 10, 20, 45, 55, or 75 μm in thespherical or angular powder filler can be removed by dry or wet sievingor inertial classification according to the size of the semiconductorchip. Further, Uranium or thorium content of samples of above Example1-Example 16 is less than 0.5 ppb, wherein the samples were dissolved inhydrofluoric acid and measured by ICP-MS.

The foregoing description refers to preferred embodiments of the presentinvention, and is not intended to limit the scope of the presentinvention. Various changes can be made to the foregoing embodiments ofthe present invention. That is to say, all simple and equivalent changesand modifications made in accordance with the claims of the presentinvention and the content of the description fall into the protectionscope of the patent of the present invention. What is not described indetail in the present invention is conventional technical content.

1. A method for preparing a spherical or angular powder filler,comprising the steps of: S1, providing a spherical or angular siloxanecomprising T units, wherein the T unit=R₁SiO₃—, and R₁ is a hydrogenatom or an organic group independently selected from C₁-C₁₈; S2,performing a heat treatment on the spherical or angular siloxane, theheat treatment temperature between 250° C. and the temperature ofoxidative decomposition of organic groups, so that silicon hydroxylgroups in the spherical or angular siloxane are condensed to obtain acondensed siloxane; and S3, adding a treatment agent to treat thecondensed siloxane to promote the condensation of silicon hydroxylgroups in the condensed siloxane to give a spherical or angular powderfiller, the treatment agent comprising a silane coupling agent and/ordisilazane, the weight percentage of the treatment agent being 0.5-50 wt%, and the quotient of the molecular weight of at least a portion of thesilane coupling agent and/or the disilazane divided by its specificgravity at 25° C. being less than or equal to
 210. 2. The methodaccording to claim 1, wherein the spherical or angular siloxane furthercomprises Q units, D units, and/or M units, wherein the Q unit=SiO₄—, Dunit=R₂R₃SiO₂—, the M unit=R₄R₅R₆SiO₂—, and each of R₂, R₃, R₄, R₅, R₆is a hydrogen atom or a hydrocarbyl independently selected from C₁-C₁₈.3. The method according to claim 1, wherein the spherical or angularsiloxane further comprises silicon dioxide particles.
 4. The methodaccording to claim 1, wherein the heat treatment temperature of S2 is250-320° C.
 5. The method according to claim 1, wherein the silanecoupling agent is at least one agent selected from silane coupling agent(R₇)_(a)(R₈)_(b)Si(M)_(4-a-b), wherein R₇, R₈ each is a hydrogen atom, ahydrocarbyl independently selected from C₁-C₁₈, a hydrocarbylindependently selected from C₁-C₁₈ replaced by functional groups,wherein the functional group is at least one group selected from thegroup consisting of following organic functional groups: vinyl, allyl,styryl, epoxy group, aliphatic amino, aromatic amino,methacryloxypropyl, acryloxypropyl, ureidopropyl, chloropropyl, mercaptopropyl, polysulfide, isocyanate propyl; and wherein is an alkoxy groupof C₁-C₁₈ or a halogen atom, a=0, 1, 2 or 3, b=0, 1, 2 or 3, and a+b=1,2 or
 3. 6. The method according to claim 1, wherein the disilazane is atleast one agent selected from disilazane (R₉R₁₀R₁₁)SiNHSi(R₁₁R₁₂R₁₃R₁₄),and wherein R₉, R₁₀, R₁₁, R₁₂, R₁₃, R₁₄ each is a hydrogen atom or ahydrocarbyl independently selected from C₁-C₁₈.
 7. The method accordingto claim 1, wherein the method further comprises removing coarseoversize particles above 1, 3, 5, 10, 20, 45, 55, or 75 μm in thespherical or angular powder filler by dry or wet sieving or inertialclassification.
 8. The method according to claim 1, wherein thespherical or angular powder filler has a particle size of 0.1-50 μm, andwherein the volatile moisture content of the spherical or angular powderfiller at 200° C. is less than or equal to 3000 ppm.
 9. The methodaccording to claim 8, wherein the spherical or angular powder filler istightly packed in the resin to form a composite material.
 10. The methodaccording to claim 9, wherein the composite material is suitable forsemiconductor packaging material, circuit board and intermediatesemi-finished product.
 11. (canceled)